EchoLink operates in one of two modes. The choice of modes is made during Setup, and can be changed at any time via the MyStation tab on the Settings screen.
Single-User Mode
Choose Single-User mode if you expect to use your PC to connect to other EchoLink stations over the Internet, using your PC's microphone and speaker to communicate. This option is appropriate if you do not expect to connect radio equipment to your PC to operate a repeater or link node.
For this mode, no special interface is required to use EchoLink. If you plan to use single-user mode, enter your callsign without any special suffix.
Sysop Mode
Choose Sysop mode if you have connected (or intend to connect) a transceiver to your PC, in order to make your rig accessible to other EchoLink users connecting over the Internet. This mode generally requires a special hardware interface between your PC and your transceiver. For more information, see Interfacing.
If you plan to use Sysop mode, enter your callsign with either a -L or -R suffix. -L signifies a Simplex Link and -R signifies a Repeater. Please use -R if your link will be tuned to the frequency pair of a local repeater (or directly connected to it), even if the callsign is not the same as that of the repeater.
Simplex Link
A simplex link is typically a transceiver tuned to a quiet simplex frequency. Stations in local range can communicate with connected stations over EchoLink, but not with each other unless they are in simplex range of each other as well.
Repeater
A repeater link is typically a transceiver tuned to the frequency pair of a local repeater. This type of link acts as a bridge between the repeater and EchoLink. Any station in range of the repeater can communicate with connected stations over EchoLink, and also with any other station in the repeater's range.
If a PC and Internet connection are available at the repeater site, it is also possible to connect EchoLink directly to the repeater equipment. One advantage of this arrangement is that it may not be necessary to rely on VOX for carrier detection. For more information, see Interfacing.